In recent years, optical detection methods have been widely used in biomedical field due to the advantages of high resolution, no damage to detected objects, and easy implementation. However, imaging depth and contrast of optical detection methods are significantly reduced by light scattering in biological tissues. Polarized light imaging methods are studied to reduce the influence of light scattering on imaging and reflect structure information of a superficial layer of a biological tissue.
It was proposed to use polarized light to image a superficial layer of a tissue to obtain birefringence information of the superficial layer of the tissue, and apply a polarized light imaging method to skin diagnosis (Journal of Biomedical Optics, July 2002, Vol. 7, No. 3). Someone has observed polarized images of normal cells and cancer cells illuminated by polarized light of different wavelengths, and proposed the possibility of identifying cancer cells with a polarized light imaging method (in Spring Topical Meetings, Optical Society of America, Orlando, Fla. (Mar. 8-11 1998)). In recent years, the polarization imaging has been applied to human tissues such as skin and blood vessels.
However, as linearly polarized light with only one polarization angle is used for illumination in the above polarization imaging methods, it is difficult to obtain overall polarization information of a biological tissue, and only the polarization information of the biological tissue can be evaluated qualitatively by the above imaging methods.